Segmental wall construction for combustion apparatus



J y 7', 1954 w. e. MARSKELL ETAL 2,684,572

' SEGMENTAL WALL CONSTRUCTION FOR COMBUSTION APPARATUS Filed Dec. 9. 1950 2 Sheets-Sheet 1 I nverilors' W417i? 6, MARS/(ELL Aftorney Patented July 27, 1954 SEGMENTAL WALL CONSTRUCTION FOR COMBUSTION APPARATUS Walter G. Marskell, Kilmacolm, and Edwin C. McKenzie, Inohinnan, Scotland, assignors to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application December 9, 1950, Serial No. 200,052

Claims priority, application Great Britain December 12, 1949 '7 Claims.

This invention relates to combustion apparatus of the kind comprising an outer casing adapted to resist internal pressure, an inner wall disposed within the outer casing, surrounded by a gas flow passage and enclosing a combustion and mixing chamber arranged to receive fuel at one end thereof and provided with an outlet for combustion and tempering gases at the other end thereof, which inner wall is formed with tempering gas inlet means. In such apparatus, in view of the pressure involved, rapid combustion at high temperature in a small space is desirable, with the result that the inner wall is required to operate under arduous conditions. The object of the invention is the provision of improved inner walls.

The invention includes combustion apparatus of the kind specified, wherein the inner wall includes inner wall sections extending round the combustion chamber periphery and arranged to overlap sufficiently and formed to provide ducts or nozzles for directing tempering gas into the chamber, at least one inner wall section required to work under the most arduous conditions is formed of more highly heat resisting material than the other inner wall section or wall sections, whilst the section or each of the sections of more highly heat resisting material is formed of a number of separate segments.

The invention also includes combustion apparatus of the kind specified, wherein the inner wall includes a plurality of sleeve-like rings of which pairs of adjacent rings overlap sufilciently and are formed to provide ducts or nozzles for directing tempering gas into the chamber, at least one of the rings required to work under the most arduous conditions is formed of more high- 1y heat resisting material than the other ring or other rings, whilst the ring or each of the rings of more highly heat resisting material is formed of a number of separate segments.

The invention will now be described, by way of example, with reference to the accompanying partly diagrammatic drawings, in which:

Figure 1 is an elevation of a combustion apparatus for supplying gases for a gas turbine in section on the axis of a combustion chamber thereof;

Figure 2 is an enlarged view of part of Figure l, but shown in perspective;

Figure 3 illustrates in sectional elevation, and Figure 4 in sectional plan, a modification of the apparatus of Figures 1 and 2.

Referring to Figures 1 and 2 of the accompanying drawings, a combustion and mixing chamber 50 enclosed by an inner wall 5! is arranged with its axis upright and is surrounded by an outer casing 52 adapted to resist internal pressure and spaced from the combustion chamber so as to leave an air flow passage 53 between the inner wall and the casing. The inner wall 5| consists of a column of six similar frusto conical rings 54 having their ends of larger diameter below the ends of smaller diameter and overlapping to provide ducts or nozzles 55 for directing air from the air flow passage 53 into the combustion chamber 50 with an upward component of motion. Leading from the chamber at the lower end thereof is an outlet duct 56 having an upper sharply converging part 51 and a lower part 58 which projects through the lower wall of the outer casing 52 and gradually diverges to a conduit 59 leading to the gas turbine.

The top of the combustion chamber is fitted with a cowl 6| of which a depending part 62 projects, with a certain amount of clearance to provide a peripheral inlet port 63, into the uppermost ring 54. The 'cowl is independently supported and provides a central port 64 for the admission into the combustion chamber of primary air past an air register 65 and of fuel from a central burner 66 arranged in operation to direct a combustible spray of oil downwardly. A windbox 67 surrounds the central port and is supplied with primary air through a duct 68. With the upper part of the interior of the outer casing communicates a second duct 69 which supplies air for completing combustion and for cooling metal parts and tempering the gases produced.

Each ring 54 is formed of separate overlapping plates 92. The plates are supported at their lower edges by projections 98 on supporting rings 94, which rings encircle the inner wall and are welded to a number of uprights whose lower ends rest upon the converging upper part 57 of the outlet duct. A stud 93 is welded to, or screwed into, or cast, or moulded with each plate adjacent the top edge thereof and where the rings overlap project through slots 91 in the lower parts of plates of the next upper ring, and through oversize bores in the supporting rings 94 to the outside thereof where they are provided with washers and nuts. Replaceable sleeve-like parts 96 through which the studs extend determine the widths of the ducts 55 between the rings.

In operation air from the duct 69 flowing to and through the ducts between the rings 54 effects cooling of the inner wall and outer casing 52, completion of combustion, and tempering of the gases produced. In view of the number of ducts and the short distance between them the pressure difference between the air flow passage 53 and the combustion chamber 56 is small and the cooling of the wall is effective. The air entering the combustion chamber through the ducts has an upward component of motion which has the result of establishing or increasing turbulence within the combustion chamber. The air is so admitted to the combustion chamber that combustion therein is not adversely aiiected, and the turbulence hastens complete combustion and the production of a suitably tempered gas stream of substantially uniform temperature. Turbulence of air in contact with the inner surface of the wall 5! promotes cooling of that wall.

A particularly turbulent condition is established in the neighbourhood of the inlet end of the chamber, since secondary air from the peripheral port 53 and air from the adjacent duct 55 between the topmost and the next adjacent ring enter the combustion chamber in directions having respectively downward and upward components of motion.

The outlet duct of converging-diverging form assists in ensuring that the gases reaching the turbine are of substantially uniform tem perature.

The width of a duct 55 may be regulated by replacing sleeve-like parts 96 of one length by sleeve-like parts 96 of another length, the nuts on the studs being re-located appropriately. By this means within the permissible pressure drop the velocities of inflow of the tempering air may, as is desirable, be varied. Also the distribution of the total inflow of tempering air amongst the difierent ducts may be varied.

The wall may be required to operate under very arduous conditions. If it is required to replace an area of the wall, fresh plates can be substituted where necessary and it is not essential to replace the whole wall or a whole ring. Another advantage is that the plates are capable of independent expansion.

The construction possesses the advantage that a ring may readily be formed of highly heat resisting material even. if such material is not, or not readily, workable to form large pieces of complicated shape. Thus a ring of very highly heat resisting metal may be formed of cast metal plates. T -e plates constituting a ring may be moulded from refractory ceramic, and in this case the studs may be moulded therewith; alternatively, the plates may comprise not only refractory but metal backing plates adapted to hold the refractory, in the form of refractory plates, removably, the studs 83 being secured as by welding to the metal backing plates.

It is found that usually conditions that call for the most highly heat resisting material will b experienced only in the upper half of the combustion chamber and towards the bottom of the combustion chamber less highly heat resisting material will sumce. Thus plates of refractory material in the upper part of the combustion chamber may be accompanied by plates of alloy in the lower part of the combustion chamber, or when plates of stainless steel suffice in the upper part of the combustion chamber first cost may be reduced by employing plates of ferritic steel in the lower part of the combustion chamber.

In tie modification of the arrangement of Figures 1 and 2 illustrated in Figures 3 and l, the width of a duct between adjacent rings consisting of overlapping plates can be adjusted during operation. Each plate E36, which is flat, of

a ring is supported near its lower end by a bolt H3! extending radially inwardly from a supporting ring Hi2 encircling the combustion chamber and secured to uprights let. Each plate can rock on its bolt and its upward and inward inclination is determined by the axial position of an adjusting ring Hi l encircling the combustion chamber, on which adjusting ring is pivoted an end of a link 1% the other end of which is pivotally connected to the plate lilil near the centre thereof. The adjusting ring lee can be moved in the vertical direction by suitable rods Hi6 extending upwardly and to the outside of the pressure casing. Downward movement of the adjusting ring from the position shown in full lines to the position shown in dotted lines will effect an increase in the width of the duct 55 through which air is admitted to the combustion chamber between the ring and the superjacent ring owing to the rocking of the plates inwardly from the full line position to the dotted line position. Alternate plates overlap the remaining plates.

lhus the width of a duct can be adjusted during operation. Adjustment during operation of the distribution of the total inflow of air between the difierent ducts may be advantageous; for example, while at higher loads he ducts be open to their maximum extent, at low loads in order to achieve proper mixing between air and fuel and proper protection of the wall it may be necessary to supply the appropriate air quantity in greater proportion near the top of the combustion chamber and to this end the lower ducts may be substantially restricted.

One or more of the illustrated constructions may also embody inventions the subject of claim in one or more of other U. S. applications by the same inventors, namely, Serial Numbers 290,051; 200,053 and 200,054.

We claim:

1. Combustion apparatus comprising an outer casing adapted to resist internal pressure, an inner wall disposed within the outer casing, surrounded by a gas flow passage and enclosing a combustion and mixing chamber arranged to receive fuel at one end thereof and vided with an outlet for combustion and tempering gases at the other end thereof, which inner wall is formed with tempering gas inlet means, whe ein the inner wall includes ring sections extending around the combustion chamber periphery and arranged to overlap sufficiently and spaced to provide not es for directing tempering gas into the chamoer, one of said ring sections being formed oi a number of separate overlapping plate segments.

2. Combustion apparatus comprising an outer casing adapted to resist internal pressure, an inner wall disposed within the outer casing, surrounded by a gas flow passage and enclosing a combustion and mixing chamber arranged to receive fuel at one end thereof and provided with an outlet for combustion and tempering gases at the other end thereof, which inner wall is formed with tempering gas inlet means, wherein the inner wall includes a plurality of sleeve-like i usto conical rings of substantially equal dimensions in which pairs of adjacent rings overlap sufficiently and are spaced to provide nozzles for directing tempering gas into the chamber, at least one of the rings required to work under the most arduous temperature conditions adjacent the fuel receiving end of said chamber is formed of more highly heat resisting material than the other rings, whilst the ring of more highly heat resisting material is formed of a number of step arate overlapping plate segments.

3. Combustion apparatus as claimed in claim 1, wherein support means are provided for each of said rings including a lower bracket and an upper stud and the separate segments of a ring are capable of expansion independently of one another.

4. Combustion apparatus as claimed in claim 1, wherein the positions of the segments of a ring are adjustable in order by moving an edge of the ring radially with respect to the axis of said com.- bustion chamber to vary the width of a nozzle.

5. Combustion apparatus as claimed in claim 1, wherein segments of high temperature resistant material are cast as substantially fiat plates with holding means therefor.

6. Combustion apparatus as claimed in claim 1, wherein the segments of said ring adjacent the fuel receiving end of said chamber include refractory and metal backing plates therefor provided with separate support means for the segments.

7. Combustion apparatus as claimed in claim 1, including at least one other ring spaced from said segmental ring and constructed of less highly heat resisting material also formed of a number of separate circumferentially overlapping segments.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,039,607 Powers May 5, 1936 2,149,182 Powers Feb. 28, 1939 2,464,791 Bonvillian Mar. 22, 1949 2,470,184 Pfenninger May 17, 1949 2,531,810 Fyffe Nov. 28, 1950 2,547,619 Buckland Apr. 3, 1951 FOREIGN PATENTS Number Country Date 255,541 Switzerland Jan. 17, 1949 

